In recent years, wearable devices have been actively developed. Because a wearable device is worn on one's body, it is preferable that the wearable device have a curved shape so as to conform to a curved surface of the body or be curved according to the movement of the body. Therefore, it is preferable that a secondary battery used in a wearable device have flexibility like those for displays and other housings.
For example, Patent Document 1 discloses an electrochemical device (e.g., a secondary battery or a capacitor) which is covered with a metal laminate and which can be easily curved or can easily maintain a curved state.